Speed limiters should be fitted to cars and lorries on a voluntary basis to reduce carbon emissions and cut accidents, a transport advisory body has recommended.

The innovation - using satellite navigation technology to read the road's speed limit and adjust the vehicle's accelerator - was given a cautious welcome by the Department for Transport yesterday.

The report by the Commission for Integrated Transport and the Motorists' Forum claimed accidents involving injuries could be cut by 12% if the system was adopted universally - with a manual override system - and by more if the speed limiter was mandatory and always on.

The Intelligent Speed Adaptation (ISA) system has been tested in the UK over 355,000 miles of driving on roads where the speed limit was known.

Urging its adoption, Sir Trevor Chinn, chairman of the Motorists' Forum, said: "The UK has an enviable record on road safety but we still kill nearly 3,000 people on our roads each year. This report shows the potential substantial savings in injury accidents that could be achieved."

Using the system on urban roads with a 30mph limit could increase fuel consumption and emissions, because cars operate more efficiently above that speed, the study acknowledges. But there should be significant reductions on roads where the limit is 70mph.

The report recommends voluntary fitting and use of the device, suggests government vehicle fleets should be equipped first of all to encourage other drivers to join the scheme, and proposes that it should be provided for newly qualified drivers and those convicted of dangerous driving.

The DfT said: "It has the potential to reduce the number of deaths and injuries on our roads ... our view [is] that it could be a useful road safety feature for drivers who wish to use it."

The technology is in its infancy and will require mapping of speed limits on every UK road. Automatic speed controls have frequently been greeted with suspicion.

The Liberal Democrat transport spokesman, Norman Baker, said yesterday: "This is a well-meaning thought but one which could have dangerous consequences. Any attempt to control speed could mean that drivers might not be able to accelerate out of dangerous situations. This could make road safety worse."

The Institute of Advanced Motorists' director of research and policy, Neil Greig, added: "ISA may be able to ensure that all cars observe speed limits, provided that critical safety conditions are met and tested. However, even with these assurances, an understandable deep-rooted concern about Big Brother will have to be overcome."